1. Field of the Invention
The present invention relates to a data redirection system and method using an Internet protocol private branch exchange (IP PBX).
2. Description of the Related Art
In much of the Internet, public IP addresses are generally limited in number, and thus need to be shared. A network address translator (NAT) enables a number of users to share public IP addresses by translating public IP address to private IP address and vice versa.
A firewall should be disposed between the Internet and a private network to protect a user's network from external attacks. When the network address translator (NAT) is disposed in a router providing a connection to the Internet, a public IP address allocated to the router is externally known and only a private IP address is used in the router. The router translates the public IP address to the private IP addresses and vice versa. A hacker needs to be aware of the private IP address in order to attack the private network, and thus the private network can be safely protected, because it is difficult for the hacker to know the private IP address.
For example, in case of a voice call, the private IP address of a media gateway interface (MGI) is first mapped in a one-to-one correspondence to the public IP address of the router to pass through the network address translator (NAT), a voice data packet received from an internal or external IP terminal is converted to a pulse code modulation (PCM) voice data, the PCM voice data is converted to a voice data packet by the a time division multiplexing (TDM) switching module, and the voice data packet is then transmitted to the other party's IP terminal.
Particularly, in converting the voice data packet to the PCM voice data, a media gateway interface (MGI) channel of the media gateway interface (MGI) is used, and 2 channels are used for each of an outgoing call and an incoming call. Two sessions are established and generated between the internal IP terminal and the external IP terminal. One is established between the internal IP terminal and the media gateway interface (MGI), and the other is established between the media gateway interface (MGI) and the external IP terminal.
As described above, the video IP terminal of a conventional IP PBX system converts the voice data packet to the PCM voice data and then converts the PCM voice data to the voice data packet again in transmitting and receiving the voice data through the media processor after establishing a VoIP call through a signal processor of the IP PBX system. The twice conversion significantly degrades a voice quality.
In addition, there is no solution of call service between a standard video session initiation protocol (SIP) terminal and an internal video IP terminal of the IP PBX system in a network address translation environment.